Polythioether prepolymers and their use in curable compositions in particular in mastics

ABSTRACT

A polythioether prepolymer including functional groups capable of being obtained by the reaction: of at least one compound T having a number f of thiol functional group number selected from 2, 3, 4 and 6, with at least one compound E having a number g of epoxy functional groups number selected from 2 and 3. Also, a method of preparation for this prepolymer, a composition including this prepolymer and an oligomer as well as its use as a mastic and a polythioether polymer obtained from this polythioether prepolymer with an oligomer.

FIELD OF INVENTION

This invention relates to the field of sealing coatings also calledsealants, based on polythioethers, and their uses in particular in theaeronautical field.

These mastics are products formed in situ using a curable compositioncomprising a prepolymer and a crosslinking/hardening agent.

BACKGROUND

Mastics based on polythioethers are already known from the prior art, inparticular in U.S. Pat. No. 6,172,179 B1 or more recently in patentapplications WO 2018/085650 and WO 2019/010457. These polythioethers areespecially prepared from prepolymers obtained by reacting a thiol with acompound comprising a double bond such as a diene. Then, at the time ofapplication, said prepolymer is placed in the presence of a hardeningagent chosen in particular from epoxy resins. These prepolymers do notcontain pendant hydroxyl groups and therefore do not have the advantagesassociated with this property.

Furthermore, it is known to those skilled in the art that linearpolymers tend to swell, that is to say they increase in bulk or involume after prolonged exposure to hydrocarbons and other lubricants.One of the solutions proposed to overcome this drawback is to usepolyfunctional agents, such as compounds having more than two reactivethiol groups, capable of producing polythioethers having a functionalitygreater than 2.

Consequently, there is always a need for new prepolymers havingparticular properties as well as compositions obtained from a prepolymerand a hardener such that at least one of the two has an averagefunctional group number greater than or equal to 2, or such that the sumof the functional group numbers of the prepolymer and of thecrosslinking agent, also called hardener, is greater than 4.

In addition, there is also always a need for new sealant compositionshaving specific chemical properties, adapted to the needs ofaeronautics.

More particularly, the inventors of this invention have sought todevelop a polythioether prepolymer having a thiol functional groupnumber greater than 2 in order to ensure that the final polymer is inthe form of a three-dimensional network.

SUMMARY

A first subject-matter of this invention relates to a polythioetherprepolymer comprising thiol functional groups (—SH), and capable ofbeing obtained by the reaction:

of at least a compound T having a number f of functional groups thiolselected from 2, 3, 4 and 6, preferably 3, 4 and 6, with at least onecompound E having a number g of epoxy functional groups selected from 2and 3.

The polythioether prepolymer therefore also comprises pendant hydroxyl(—OH) functional groups.

Advantageously during the reaction of at least one compound T and atleast one compound E, the compounds T comprising thiol groups and thecompounds E comprising epoxy groups react together according to a rationumber of thiol groups:number of epoxide groups from 3:1 to 4:1.

The polythioether prepolymer according to the invention has an averagethiol functional group number greater than or equal to 2, preferablygreater than or equal to 3, thus this prepolymer is capable of producingpolymers in development, in three dimensions.

According to a first aspect, the polythioether prepolymer according tothe invention has an average thiol functional group number ranging from3 to 6 and preferably equal to 3, this preferred variant makes itpossible to prepare compositions which will crosslink to give athree-dimensional network, at a speed crosslinking controllabledepending on the amount of catalyst.

According to a second aspect, the polythioether prepolymer according tothis invention, optionally according to the first aspect, has amolecular weight ranging from 1000 g/mol at 6000 g/mol, preferably 3000g/mol at 6000 g/mol. The molecular weight distribution of thepolythioether prepolymer is determined by steric exclusionchromatography (CES) advantageously on a column separating the highmolecular weights (1000-2000000 g/mol), whose solvent is Tetrahydrofuran(THF).

According to a third aspect, the polythioether prepolymer according tothis invention, optionally according to at least one of the first andsecond aspects, has a glass transition temperature Tg ranging from −60°C. to −30° C., preferably ranging from −40° C. to −35° C. The glasstransition temperature is considered to be the start (onset) of thephase transition determined using a differential scanning calorimeter(DSC).

The analysis consists of a scan of −70° C. to +0° C. at a speed of 10°C./min under a constant flow of nitrogen in accordance with ISO standard11357-3:2018.

According to a fourth aspect, the polythioether prepolymer according tothis invention optionally according to at least one of the first, secondand third aspects, has a viscosity of 100 to 500 Pa·s, preferably of 350Pa·s The measurement is carried out on a geometry rheometer cone/plan atan oscillating speed of 0.5 s⁻¹, as defined in the ISO standard11443:2014. These prepolymers are therefore liquid at room temperature(20° C.) and atmospheric pressure.

A second subject-matter of this invention relates to a method forpreparing the polythioether prepolymer according to this inventioncomprising at least the following steps:

-   -   having at least one compound T having a number f of thiol        functional groups (—SH) chosen from the group made up of        functional groups 2, 3, 4 and 6;    -   adding to said compound T at least one compound E having a        number g of epoxide functional groups chosen from the group        constituted by functional groups 2 and 3, advantageously in an        amount such as the ratio number of thiol groups:number of        epoxide groups ranging from 3:1 at 4:1;    -   adding a catalyst before and/or after adding said compound E,    -   stirring the reaction mixture comprising compound E, compound T        and the catalyst,    -   recovering the polythioether prepolymer.

A third subject-matter of this invention relates to a curablecomposition as well as its use as a sealant or sealant.

The sealant compositions according to the invention also have specificchemical properties, in particular properties of resistance to solventssuch as hydrocarbons, water especially salt water and hydraulic fluids,more particularly it has been observed that the mechanical properties ofsaid compositions according to the invention are kept when they areplaced in the presence of these solvents: no swelling is observed. Inaddition, the compositions according to the invention exhibit goodadhesion to their support even during the subsequent application of asolvent to said support.

In particular, the composition according to this invention when it ishardened, preferably has a hardness ranging from 20 to 100 Shore A,preferably from 40 to 70 Shore A, determined by penetration by means ofa durometer according to ISO standard 868: 2003 of Jan. 3, 2003.

Other aspects, advantages, properties of this invention are presented inthe description and the examples which follow.

DETAILED DESCRIPTION Definitions

Within the meaning of the invention, “prepolymer” is meant to beunderstood as an oligomer or a polymer having reactive groups whichallow it to participate in a subsequent polymerization and thus toincorporate several monomer units in at least one chain of the finalmacromolecule.

Within the sense of the invention, “polythioether” is meant to beunderstood as a compound comprising at least two thioether groups, thatis to say “CSC” groups.

In the sense of the invention, “hardener” is meant to be understood as acompound capable of reacting with the prepolymer. The hardening compoundis also called a “crosslinking agent”.

Within the meaning of the invention, “curable composition” is meant tobe understood as a composition comprising a prepolymer and a hardenerwhich react spontaneously to give a cured composition comprising acrosslinked polymer.

Generally, the final polymer does not substantially comprise any morereactive functions.

Polythioether Prepolymer

The polythioether prepolymer according to this invention comprises thiolfunctional groups, that is to say —SH, terminals, linked to a carbonatom C, these thiol functional groups are capable of reacting with thereactive functions of the oligomer used as crosslinking agent during theuse of the curable composition according to the invention. The thiolfunctional groups are terminal groups, that is to say that saidpolythioether prepolymer according to this invention does not comprisependant thiol groups in the backbone.

The prepolymer according to this invention is not crosslinked. In fact,the prepolymer must be able to react, via its terminal thiol groups,with the reactive functions of the oligomer used as crosslinking agentto give the final hardened composition. In particular, the crosslinkingrate of the polymer present in the final composition according to theinvention makes it suitable for use as a sealant or mastic.

As mentioned above, the polythioether prepolymer according to thisinvention is capable of being obtained by the reaction:

of at least one compound T, which is a polythiol, having a number f ofthiol functional groups selected from 2, 3, 4 and 6, preferably 3, 4 and6, with at least one compound E, which is an epoxy, having a number g ofepoxy functional groups selected from 2 and 3.

“functional group number of a compound” is meant to be understood as thefunctionality that is the number of functions, that is to say ofreactive groups, present in this compound—still called a monomer —,these reactive functions being capable of participating in a chemicalreaction leading to the chain growth—that is, polymer —.

In this invention, the reactive functions of compound T are the thiolfunctions and the reactive functions of compound E are the epoxidefunctions.

“Epoxy” function is meant to be understood as a group comprising anoxygen bridged on a carbon-carbon bond. In this text the terms “epoxy”and “epoxides” are used interchangeably.

As already mentioned, the compounds T and E, as well as their respectiveamounts, are chosen so as to lead to a prepolymer of average thiolfunctional group number greater than or equal to 2, preferably greaterthan or equal to 3.

In particular, the reaction for preparing the polythioether prepolymeris performed with at least one compound T comprising thiol groups and atleast one compound E comprising epoxy groups according to a ratio numberof thiol groups:number of epoxide groups from 3:1 at 4:1.

“Number of thiol groups” and “number of epoxide groups” is meant to beunderstood as the number of groups which participate in the reaction.

Furthermore, advantageously the compounds T and E do not comprisereactive carbon-carbon double bonds, that is to say reactive alkenylfunctions, nor reactive carbon-carbon triple bonds, that is to sayreactive alkynyl functions.

According to a first preferred embodiment of the invention, thepolythioether is obtained by the reaction of at least one compound T,having a number f of thiol functional groups selected from of 3, 4 and6, with at least one compound E, having a number g of epoxy functionalgroups selected from 2 and 3.

According to a second preferred embodiment of the invention, thepolythioether prepolymer is obtained by the reaction of at least onecompound T, having a number of thiol functional groups equal to 2 withat least one compound E, having a number g of functional groups equal to3.

Furthermore, said polythioether prepolymer according to the inventionalso includes pendant hydroxyl (—OH) functional groups. These groups areobtained following the opening of the epoxy cycles during the reactionof said epoxy cycles of the compounds E with the thiol groups of thecompounds T. More particularly, the polythioether prepolymer comprisesthioether groups, —S—CH₂—CH(OH)— with S linked to a carbon atom.

In this text the terms “hydroxy” and “hydroxyls” are usedinterchangeably.

Without wishing to be bound by any theory, it seems that the variousgroups present in the polythioether prepolymer according to theinvention make it possible to obtain advantageous properties, inparticular in terms of chemical resistance mainly to hydrocarbons, waterespecially salty water and hydraulic fluids due in particular to thepresence of thioether units with pendant hydroxyl groups —S—CH₂—CH(OH)—and in terms of adhesion due in particular to the presence of pendanthydroxyl groups. In addition, said polythioether prepolymer can beformulated so as to have a structure having a functional group numberequal to 3, particularly capable of leading to a curable compositionwhose crosslinking speed is controllable.

As already mentioned, the reaction mixture comprises the compounds whichtake part in the reaction, in particular the compound (s) E, or thecompound(s) T and the catalyst.

Advantageously, the reaction mixture does not include other compoundscomprising reactive functions, different from compounds E and compoundsT.

Advantageously, the reaction mixture does not comprise compounds chosenfrom compounds comprising one or more reactive double-bonds also calledalkenyl groups and compounds comprising one or more reactivetriple-bonds also called alkenyl groups.

Advantageously, the reaction mixture consists of compound E, compound Tand the catalyst.

Advantageously, the polythioether prepolymer according to the inventionis obtained from at least one compound T comprising at least two groupschosen from the following groups:

b) —(CH₂)_(nb)—SH;

c) —(CH₂)_(nc)—O—(CH₂)_(mc)—SH;

d) —(CH₂)_(nd)—O—(CO)—(CH₂)_(md)—SH;

e) —(CH₂)_(ne)—(CO)—O—(CH₂)_(me)—SH;

f) —(CH₂)_(nf)—O—(CH₂CH₂O)_(lf)—(CH₂)_(mf)—SH;

g) —(CH₂)_(ng)—(CO)—O—(CH₂CH₂O)_(lg)—(CH₂)_(mg)—SH;

h) —(CH₂)_(nh)—O—(CO)—(CH₂CH₂O)_(lh)—(CH₂)_(mh)—SH;

i) —(CH₂)_(ni)—O—(CH₂CH₂O)_(li)—(CO)—(CH₂)_(mi)—SH;

j) —(CH₂)_(nj)—O—(CO)—(CH₂CH₂O)_(lj)—(CO)—(CH₂)_(mj)—SH; and

k) —(CH₂)_(nk)—(CO)—O—(CH₂CH₂O)_(lk)—(CO)—(CH₂)_(mi)—SH;

each of nb, nc, nd, ne, nf, ng, nh, ni, nj, nk being an integer rangingfrom 0 to 10; each of mc, md, me, mf, mg, mh, mi, mj, mk being aninteger ranging from 0 to 10; and each of lf, lg, lh, li, lj, lk aninteger ranging from 0 to 6.

Within the meaning of this application, an “integer ranging from 0 to10”, is meant to be understood as said integer being able to take thevalues 0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10 and by “integer ranging from 0to 6”, within the meaning of this application, is meant to be understoodas said integer being able take the values 0; 1; 2; 3; 4; 5; 6.

According to a first variant of the invention, the polythioetherprepolymer is obtained from at least one compound T of general formula(I):

in which R₁, R₂ and R₃, identical or different, preferably identical,are chosen from the following groups:

a) —C₁₋₁₀ alkyl;

b) —(CH₂)_(n1b)—SH;

c) —(CH₂)_(n1c)—O—(CH₂)_(m1c)—SH;

d) —(CH₂)_(n1d)—O—(CO)—(CH₂)_(m1d)—SH;

e) —(CH₂)_(n1e)—(CO)—O—(CH₂)_(m1e)—SH;

f) —(CH₂)_(n1f)—O—(CH₂CH₂O)_(l1f)—(CH₂)_(m1f)—SH;

g) —(CH₂)_(n1g)—(CO)—O—(CH₂CH₂O)_(l1g)—(CH₂)_(m1g)—SH;

h) —(CH₂)_(n1h)—O—(CO)—(CH₂CH₂O)_(l1h)—(CH₂)_(m1h)—SH;

i) —(CH₂)_(n1i)—O—(CH₂CH₂O)_(l1i)—(CO)—(CH₂)_(m1i)—SH;

j) —(CH₂)_(n1j)—O—(CO)—(CH₂CH₂O)_(l1j)—(CO)—(CH₂)_(m1j)—SH and

k) —(CH₂)_(n1k)—(CO)—O—(CH₂CH₂O)_(l1k)—(CO)—(CH₂)_(m1k)—SH;

each of nib, n1c, n1d, n1e, n1f, n1g, n1h, n1i, n1j, n1k being aninteger ranging from 0 to 10; each of m1c, m1d, m1e, m1f, m1g, m1h, m1i,m1j, m1k is an integer ranging from 0 to 10; and each of l1f, l1g, l1h,l1i, l1j, l1k being an integer ranging from 0 to 6; provided that atleast two radicals from the radicals R₁, R₂ and R₃ are chosen fromgroups b) to k).

Said polythioether prepolymer can be obtained from several compounds T,of general formula (I) in which R₁, R₂ and R₃, preferably identical, arechosen, for each of the compounds T, from groups (a) to (k) as definedabove and on the condition that, for each of the compounds T, at leasttwo radicals from the radicals R₁, R₂ and R₃ are chosen from groups b)to k).

Preferably said compound T of formula (I) has a number f of thiolfunctional groups equal to 3, that is to say that the radicals R₁, R₂and R₃ are chosen from groups b) to k).

Advantageously, said polythioether prepolymer is obtained from at leastone compound T of general formula (I) in which R₁, R₂ and R₃, which areidentical, are chosen from the groups d)—(CH₂)_(n1d)—O—(CO)—(CH₂)_(m1d)—SH or e)—(CH₂)_(n1e)—(CO)—O—(CH₂)_(m1e)—SH, preferably R₁, R₂ and R₃ are chosenfrom the group d) —(CH₂)_(n1d)—O—(CO)—(CH₂)_(m1d)—SH; n1d, m1d, n1e andm1e each being an integer ranging from 0 to 10.

In particular, said compound T corresponds to the general formula (I) inwhich R₁, R₂ and R₃ are groups d): —(CH₂)_(n1d)—O—(CO)—(CH₂)_(m1d)—SHwith n1d=2 or m1d=2, i.e. thetris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate of formula:

This compound is sold in particular by the company Worlée under the nameTHIOCURE® TEMPIC., having a molar mass M: 525 g/mol and of equivalentweight TEW thiols 180-184g/eq.

According to a second variant of the invention, the polythioetherprepolymer is obtained from at least one compound T of the generalformula (II):

in which R₄, R₅, R₆ and R₇, identical or different, are chosen from thefollowing groups:

a) —C₁₋₁₀ alkyl;

b) —(CH₂)_(n2b)—SH;

c) —(CH₂)_(n2c)—O—(CH₂)_(m2c)—SH;

d) —(CH₂)_(n2d)—O—(CO)—(CH₂)_(m2d)—SH;

e) —(CH₂)_(n2e)—(CO)—O—(CH₂)_(m2e)—SH;

f) —(CH₂)_(n2f)O—(CH₂CH₂O)_(l2f)—(CH₂)_(m2f)—SH;

g) —(CH₂)_(n2g)—(CO)—O—(CH₂CH₂O)_(l2g)—(CH₂)_(m2g)—SH;

h) —(CH₂)_(n2h)—O—(CO)—(CH₂CH₂O)_(l2h)—(CH₂)_(m2h)—SH;

i) —(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH;

j) —(CH₂)_(n2j)—O—(CO)—(CH₂CH₂O)_(l2j)—(CO)—(CH₂)_(m2j)—SH and

k) —(CH₂)_(n2k)—(CO)—O—(CH₂CH₂O)_(l2k)—(CO)—(CH₂)_(m2k)—SH

each of n2b, n2c, n2d, n2e, n2f, n2g, n2h, n2i, n2j, n2k being aninteger ranging from 0 to 10; each of m2c, m2d, m2e, m2f, m2g, m2h, m2i,m2j, m2k being an integer ranging from 0 to 10; each of l2f, l2g, l2h,l2i, l2j, l2k being an integer ranging from 0 to 6; with the provisothat at least two radicals from the radicals R₄, R₅, R₆ and R₇ arechosen from groups b) to k).

Said polythioether prepolymer can be obtained from several compounds T,of the general formula (II) in which R₄, R₅, R₆ and R₇, are chosen, foreach of the compounds T, from groups (a) to (k) and on the conditionthat, for each of the compounds T, at least two radicals from theradicals R₄, R₅, R₆ and R₇ are chosen from groups b) to k).

Preferably said compound T of formula (II) has a number f of thiolfunctional groups equal to 3 or 4, that is to say that three or fouramong the radicals R₄, R₅, R₆ and R₇ are chosen from groups b) to k).

Advantageously, according to a first variant, the polythioetherprepolymer is obtained from at least one compound T of general formula(II) in which R₄, R₅ and R₆, which are identical, are chosen fromgroups: h) —(CH₂)_(n2h)—O—(CO)—(CH₂CH₂O)_(l2h)—(CH₂)_(m2h)—SH or i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH and R₇ is chosen fromthe group a) —C₁₋₁₀ alkyl, preferably R₄, R₅, and R₆, which areidentical, are chosen from the group i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH and R₇ is selectedfrom the group a) —C₁₋₁₀ alkyl.

Preferably, said compound T corresponds to the general formula (II) inwhich R₄, R₅ and R₆ are groups i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH with n2i=0 and m2i=2;and R₇ is a methyl group, that is to say a compound of formula:

This compound in which L2i ranges from 1 to 5.7 is trimethylolpropanetri (3-mercaptopropionate) ethoxylated, in particular marketed by thecompany Worlée under the name Thiocure® ETTMP 1300 of molar mass M: 1274g/mol and of equivalent weight thiols TEW:435-438 g/eq.

This compound in which L2i=0 is trimethylolpropane tri(3-mercaptopropionate), in particular marketed by the company Worléeunder the name Thiocure® TMPMP of molar mass M 399 g/mol and of a weightequivalent to TEW thiols:136-140 g/eq.

According to another preferred embodiment, said compound T correspondsto the general formula (II) in which R₄, R₅, R₆ and R₇, which areidentical, are chosen from the groups h)—(CH₂)_(n2h)—O—(CO)—(CH₂CH₂O)_(l2h)—(CH₂)_(m2h)—SH or i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH, preferably in thegroup i) —(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH.

According to a first variant of the invention, the polythioetherprepolymer is obtained from at least one compound T of general formula(III):

in which R₈, R₉, R₁₀, R_(8′), R_(9′) et R_(10′), identical or different,preferably identical, are chosen from the following groups:

a) —C₁₋₁₀ alkyl;

b) —(CH₂)_(n3b)—SH;

c) —(CH₂)_(n3c)—O—(CH₂)_(m3c)—SH;

d) —(CH₂)_(n3d)—O—(CO)—(CH₂)_(m3d)—SH;

e) —(CH₂)_(n3e)—(CO)—O—(CH₂)_(m3e)—SH;

f) —(CH₂)_(n3f)—O—(CH₂CH₂O)_(l3f)—(CH₂)_(m3f)—SH;

g) —(CH₂)_(n3g)—(CO)—O—(CH₂CH₂O)_(l3g)—(CH₂)_(m3g)—SH;

h) —(CH₂)_(n3h)—O—(CO)—(CH₂CH₂O)_(l3h)—(CH₂)_(m3h)—SH;

i) —(CH₂)_(n3i)—O—(CH₂CH₂O)_(l3i)—(CO)—(CH₂)_(m3i)—SH;

j) —(CH₂)_(n3j)—O—(CO)—(CH₂CH₂O)_(l3j)—(CO)—(CH₂)_(m3j)—SH and

k) —(CH₂)_(n3k)—(CO)—O—(CH₂CH₂O)_(l3k)—(CO)—CH₂)_(m3k)SH

each of n3b, n3c, n3d, n3e, n3f, n3g, n3h, n3i, n3j, n3k being aninteger ranging from 0 to 10; each of m3c, m3d, m3e, m3f, m3g, m3h, m3i,m3j, m3k being an integer ranging from 0 to 10; and each of l3f, l3g,l3h, l3i, l3j, l3k being an integer ranging from 0 to 6; provided thatat least two radicals from the radicals R₈, R₉, R₁₀, R_(8′), R_(9′), etRand R_(10′), are chosen from groups b) to k).

The polythioether prepolymer may be obtained from several compounds T,of general formula (III) in which R₈, R₉, R₁₀, R_(8′), R_(9′), andR_(10′), preferably identical, are chosen, for each of the compounds T,from groups (a) to (k) as defined above and on the condition that atleast two radicals from the radicals R₈, R₉, R₁₀, R_(8′), R_(9′), etR_(10′), are chosen from groups b) to k).

Preferably said compound T of formula (III) has a number f of thiolfunctional groups equal to 6, that is to say that the radicals R₈, R₉and R₁₀, R_(8′), R_(9′), et R_(10′), are chosen from groups b) to k).

Advantageously, the polythioether prepolymer is obtained from at leastone compound T of general formula (III) in which R₈, R₉, R₁₀, R_(8′),R_(9′), et R_(10′), which are identical, are chosen from groups h)—(CH₂)_(n3h)—O—(CO)—(CH₂CH₂O)_(l3h)—(CH₂)_(m3h)—SH or i)—(CH₂)_(n3i)—O—(CH₂CH₂O)_(l3i)—(CO)—(CH₂)_(m3i)—SH, preferably R₈, R₉,R₁₀, R_(8′), R_(9′) and R_(10′), which are identical, are chosen fromthe group i) —(CH₂)_(n3i)—O—(CH₂CH₂O)_(l3i)—(CO)—(CH₂)_(m3i)—SH.

In particular, the compound of formula (III) is such that n3i=0, l3i=0and m3i=2, that is to say dipentaerythritol hexa (3-mercaptopropionate),in particular marketed by the Worlée company under the name Thiocure®DiPETMP of a molar mass M: 783 g/mol and of equivalent TEW thiolsweight: 135-140 g/eq.

According to a fourth variant of the invention, the polythioetherprepolymer is obtained from at least one compound T of the generalformula (IV): HS—R₁₁—SH with R₁₁ chosen from the following groups:—(CH₂)_(q)—(CO)—O—(CH₂CH₂)—O—(CO)—(CH₂)_(s)—;—[(CH₂)_(q)—O]_(r)(CH₂)_(s)— and —[(CH₂)_(q)—S]_(r)—(CH₂)_(s)—, where qis an integer ranging from 2 to 6, r is an integer ranging from 1 to 5and s is an integer ranging from 2 to 10.

When the polythioether prepolymer according to the invention is preparedfrom only one or more compound (s) T of formula (IV), then compound E ischosen from the compounds of formula (VI).

Preferably the compound of formula (IV) is chosen from the group formedby the di (3-mercaptopropionate) of glycol of the formula:HS—(CH₂)₂—(CO)—O—(CH₂CH₂)—O—(CO)—(CH₂)₂—SH; dimercaptodioxaoctane (DMDO)of the formula: HS—[(CH₂)₂—O]₂—(CH₂)₂—SH and thedimercaptodiethylsulfide of the formula: HS—[(CH₂)₂—S]—(CH₂)₂—SH. DMDOhas a TEW thiols equivalent in weight to 91.15 g/eq.

The di(3-mercaptopropionate) glycol is marketed in particular by theWorlée company under the name Thiocure® GDMP with a molar mass M 238g/mol and with a weight equivalent to TEW thiols:122-125 g/eq.

The polythioether prepolymer according to this invention can be obtainedfrom several different T compounds, in particular 2, 3 or 4 T compounds,each chosen from the compounds of general formulas (I), (II), (III), and(IV). Mixtures of compounds T chosen from the compounds of generalformulas (I), (II), (III), and (IV), preferably from the compounds ofgeneral formulas (I), (II) and (III), all proportions can be carried outin particular as a function of the average thiol functional group ofsaid desired polythioether prepolymer.

Advantageously, the polythioether prepolymer is obtained from at leastone compound E of formula (V):

with R is a group —C₁₋₆ Alk-O—R′—C₁₋₆ Alk- and R′ is a group comprisingat least one radical chosen from the radicals: —C₁₋₆ Alk; —C₁₋₆ Alk-O—;—C₆₋₁₀ Aryl-; —C₆₋₁₀ Aryl-O—; the radicals —C₆₋₁₀ Aryl-; —C₆₋₁₀ Aryl-O—being unsubstituted or substituted by at least one group chosen from—C₁₋₆ alkyl and epoxide.

Preferably R′ does not include groups capable of reacting with a thiolgroup with the exception of epoxy groups.

Preferably R′ is chosen from the group consisting of the followinggroups:

-   -   (C₁₋₆ Alk-O—)_(n)—;    -   C₆₋₁₀ Aryl-(C₁₋₆ Alk-C₆₋₁₀ Aryl-O—)—;    -   C₆₋₁₀ Aryl-(C₁₋₆ Alk-C₆₋₁₀ Aryl-)-;

C₆₋₁₀ Aryl-C₁₋₆ Alk-C₆₋₁₀ Aryl-substituted epoxy-C₁₋₆ Alk-C₆₋₁₀ Aryl-;with n being between 0 and 5.

Within the meaning of the invention:

“Alk” is meant to be understood as an alkyl or alkylene group.

“—C₁₋₆ Alk-” means a linear or branched alkylene chain comprising from 1to 6 carbon atoms; preferably a methylene (—CH₂—) or ethylene(—CH₂—CH₂—) group; —C₆₋₁₀ Aryl- means an arylene group, that is to sayan aromatic cyclic group comprising from 6 to 10 carbon atoms,preferably a phenylene group.

Preferably the molar mass of compound E of formula (V) ranges from 300to 700 g/mol.

According to a first variant, said compound E is the diglycidyl ether ofbisphenol A, also called DGEBA, of formula

This product is sold specifically under the name Epon®828 by the companyHexion. Its molar mass M is 340.42 g/mol and its equivalent weight ofepoxides (EEW) ranging from 185 to 192g/eq.

Compound E can also be in the form of butadiene beads in diglycidylether of bisphenol A (DGEBA), this product is marketed under the nameKane Ace MX @154 by the Kaneka® company, with an equivalent weight ofepoxides (EEW): 301 g/eq.

According to a second variant, compound E corresponds to the formula ofdiglycidyl ether of bisphenol F, also called DGEBF, of formula:

This product is sold specifically under the name DER 354 by The DowChemical Company. Its molar mass M is 345 g/mol and its equivalentweight of epoxides (EEW) range from 150 to 180 g/eq.

According to a third variant, the compound E corresponds to the formula(VI):

in which n ranges from 0 to 1.

These products are in particular novolak epoxy resins marketed under thename DEN 438® by the Dow company, its equivalent weight of epoxides(EEW) ranges from 176 to 181 g/eq.

According to a third variant, the compound E corresponds to the formula:

in which n ranges from 1 to 3.

These products are specifically epoxy resins marketed under the nameD.E.R. 732P by the Dow company, its equivalent weight of epoxides (EEW)ranges from 310 to 330 g/eq.

As already mentioned, this invention also relates to a method to preparethe polythioether prepolymer according to this invention comprising atleast the following steps:

having at least one compound T having a number f of thiol functionalgroups selected from 2, 3, 4 and 6;

-   -   adding to said compound T at least one compound E having a        number g of epoxide functional groups selected from 2 and 3,        advantageously in an amount such as the ratio number of thiol        groups:number of epoxide groups ranges from 3:1 to 4:1;    -   adding a catalyst before and/or after adding said compound E,    -   stirring the reaction mixture comprising compound(s) E,        compound(s) T and the catalyst,    -   recovering the polythioether prepolymer obtained.

Advantageously, the amount of compound(s) T ranges from 60 to 80 molesper 100 moles of reaction mixture, preferably the amount of compound(s)T ranges from 60 to 80% in moles relative to the sum of compound(s) Tand compound(s) E.

Advantageously, the preparation of the prepolymer is carried out usingtwo different T compounds.

Advantageously, the amount of compound(s) E ranges from 20 to 40 molesper 100 moles of reaction mixture, preferably the amount of compound(s)E ranges from 20 to 40% in moles relative to the sum of compound(s) Tand compound(s) E.

Advantageously, the molar ratio of the compound (s) T:the compound (s) Eis between 3:1 and 4:1.

When several T compounds and/or E are used, the molar ratio of thecompound(s) T/the compound(s) E corresponds to the ratio of the weightedsums of the functional group numbers, that is to say the ratio:

Σ (molar percentage of each compound T×functional group number of saidcompound T)/Σ (molar percentage of each compound E×functional groupnumber of said compound E).

Thus the prepolymer is prepared with a molar excess of compounds T andan excess of thiol groups relative to the epoxy groups. The prepolymercomprises thiol groups in particular present on the surface of theprepolymer, these thiol groups of the prepolymer will be capable ofreacting with the reactive functions of another monomer, oligomer.

As catalyst which can be used, mention may be made of1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or N, N-dimethylbenzylamine.Generally the amount of catalyst used ranges from 0.001 to 5% preferablyfrom 0.1 to 2 and preferably from 0.2 to 1% by weight relative to theweight of the reaction medium preferably relative to the sum of thecatalysts' weights, of compound(s) E and compound(s) T.

Usually the reaction is carried out at room temperature, however thereaction being exothermic, the temperature increases spontaneouslyduring the reaction up to a temperature of between 60 and 70° C. Ifnecessary, the reaction is carried out in a container fitted with acooling system. Generally, the reaction time is from 10 to 120 minutes,preferably from 20 to 60 minutes.

The reaction between compound(s) E and compound(s) T is generallycarried out without solvents. However, a solvent can be used, it is inparticular chosen from the group consisting of ethyl acetate, 3 methylbutyl acetate, 3 methyl ethyl acetate, toluene, xylene.

Curable Composition

This invention also relates to a composition comprising at least onepolythioether prepolymer according to the invention or preparedaccording to the preparation method according to the invention, saidpolythioether prepolymer having a thiol functional group number selectedfrom 2, 3, 4, 5 and 6, and at least one oligomer chosen from modified(meth) acrylate oligomers and epoxy prepolymers, the sum of thefunctional group number of the polythioether prepolymer and thefunctional group number of the oligomer being greater than 4.

This composition is curable by the formation of a crosslinked polymer,the composition can also be qualified as a polymerizable/cross-linkedcomposition.

This invention also relates to a composition comprising at least onepolythioether prepolymer according to the invention or preparedaccording to the preparation method according to the invention, saidpolythioether prepolymer having a thiol functional group number chosenfrom 2, 3, 4, 5 and 6, and at least one oligomer chosen from modified(meth) acrylate oligomers and epoxy prepolymers, the sum of the thiolfunctional group number of the polythioether prepolymer and thefunctional group number of the oligomer being greater than 4.

Generally, the composition is obtained from at least one polythioetherprepolymer and from at least one oligomer in a polythioetherprepolymer:oligomer molar ratio ranging from 0.7/1 at 1.3/1, preferablyranging from 0.9/1 at 1.1/1 and preferably an approximatelystoichiometric ratio 1/1.

Oligomers

According to a first variant of the composition, the oligomer is amodified (meth) acrylate oligomer, preferably a di, tri or tetramodified (meth) acrylate oligomer, having a (meth) acrylate functionalgroup number selected from 2, 3, 4, 5 and 6, the sum of the thiolfunctional group number of the polythioether prepolymer and the (meth)acrylate functional group number of the modified (meth) acrylateoligomer being greater than 4.

Modified (meth) acrylate oligomers are oligomers onto which acrylate ormethacrylate terminations have generally been introduced bypolyaddition. Preferably the modified (meth) acrylate oligomer is a di,tri or tetra modified (meth) acrylate oligomer.

Preferably, the modified (meth) acrylate oligomer is chosen from thegroup formed by modified (meth) acrylate urethanes, modified (meth)acrylate butadienes, modified (meth) acrylate aliphatic ethers,bisphenol A diglycidyl ether. modified (meth) acrylate.

By way of example of modified (meth) acrylate oligomers which can beused in the compositions according to this invention, mention may bemade of urethane methacrylate sold under the name CN 1964 by the companySartomer® (Arkema group), polybutadiene diacrylate also called PBDDAmarketed under the name SR 307 by the company Sartomer®, the neopentylglycol methacrylate marketed under the name SR 802 by the companySartomer® and the 2 bisphenol A ethoxylated dimethacrylate also calledBPA2EODMA marketed under the name SR 348 L by the company Sartomer®.

According to a second variant of the composition, the oligomer is anepoxy prepolymer, the sum of the thiol functional groups of thepolythioether prepolymer and of the epoxy functional groups of theoligomer being greater than 4.

By way of example of epoxy prepolymers which can be used in thecompositions according to this invention, mention may be made of thepolyglycidyl ethers of bisphenol A, such as the epoxy resins Epon® 828,and the diepoxides of bisphenol F, such as Epon® 862, sold. by HexionSpecialty Chemicals, Inc. Epoxy pre-polymers containing Core ShellRubber can also be used. Mention may also be made of the polyepoxideswhich are obtained by epoxidation of an olefinically unsaturatedalicyclic compound, the polyepoxides which are obtained by epoxidationof an unsaturated olefinically unsaturated cyclic compound, thepolyepoxides containing oxyalkylene groups and the novolak epoxy resins.Other compounds containing epoxy groups which can be used are theepoxidized bisphenol A novolaks, the epoxidized phenolic novolaks, theepoxidized cresyl novolak.

The composition according to the invention is advantageously atwo-component composition, that is to say two parts, part A and part B,which are stored separately and mixed at the time of use.

Said composition is curable, that is to say that the two partsconstituting this composition: the basic composition called compositionpart B comprising the polythioether prepolymer according to theinvention and the accelerator called composition-part A comprising theoligomer are likely to react as a reaction ofpolymerization/crosslinking when brought together; this reaction leadingto a cross-linked three-dimensional polymer.

Preferably this reaction is carried out under substantiallystoichiometric conditions, that is to say with amounts of reagents suchthat the number of thiol functions—of the polythioether prepolymer—isequal to the number of functions capable of reacting with the thiolfunctions of the prepolymer chosen from the (meth) acrylate and epoxyfunctions.

This reaction can be carried out in the presence of a catalyst. However,this reaction is preferably carried out without adding a catalyst, otherthan the one already used during the preparation of the polythioetherprepolymer.

Advantageously, the reaction takes place without being activating by anexternal source of energy. The reaction is generally carried out undermild conditions, in particular at room temperature, 20° C.

Advantageously, the composition according to the invention comprises atleast one filler chosen from organic fillers and inorganic fillers,preferably the amount of filler(s) is between 0 and 50% by weightrelative to the total weight of said composition. As inorganic fillers,there may be mentioned: calcium carbonate, vitreous silica, silicatesespecially chosen from the group formed by talc, mica, kaolin. Thefollowing polymers may be mentioned as organic fillers: polyethylene PE,polyamide (PA), polyimide (PI) and polyphenylene sulfone (PPS).

The part A composition generally comprises at least one additive chosenfrom the group consisting of adhesion promoters, pigments, plasticizers,surfactants, rheology modifying agents. The amount in each of theadditives of the composition part A is generally between 0 and 10% byweight relative to the total weight of the composition part A.

The part B composition generally comprises at least one additive chosenfrom the group consisting of adhesion promoters, pigments, plasticizers,surfactants, rheology modifying agents. Part B preferably comprises anadhesion-promoting silane compound.

The amount in each of the additives of the composition part B isgenerally between 0 and 10% by weight relative to the total weight ofcomposition part B.

Generally the amount of the composition part A ranges from 30% to 70%;preferably 50% by weight relative to the total weight of the curablecomposition. Generally the amount of the composition part B ranges from30% to 70%; preferably 50% by weight relative to the total weight of thecurable composition.

Advantageously, the composition according to this invention is used as asealant or mastic, that is to say products capable of blocking thepassage of water, water vapor, liquid or gaseous solvents, preferablycomprising at least one organic or inorganic filler. After crosslinking,the composition according to the invention acquires properties ofresistance to solvents, in particular to hydrocarbons.

Generally, part A and part B are mixed and the composition according tothis invention thus obtained is applied to or on the area to be sealed.

The examples which follow are intended to illustrate the inventionwithout limiting its scope.

EXAMPLES Example 1 Compliant

The polyether prepolymer PTE1 is prepared in the following manner:compounds Tare introduced into a container in the quantities mentionedin table 1, then compounds E are added in the quantities mentioned intable 1 as well as the catalyst, and they are stirred. Stirring iscontinued for 30 minutes. The reaction is exothermic, the temperature iscontrolled, which goes from 20 to 70° C. The polyether PTE1 prepolymerformed is recovered. The ratio number of thiol groups/number of epoxygroups is 3.3.

Then a mastic composition according to the invention was prepared bymixing 10g of composition Part B1 containing the polyether prepolymerPTE1 according to the invention and 50g of composition Part A1containing a modified methacrylate oligomer. The components of the PartB1 and Part A1 compositions are listed in Table 1.

TABLE 1 Composition of PTE 1 Number of Quantity thiol or epoxy ComponentName (in g) groups Compound T of Thiocure ® 35.28 0.255 thiol eq.functional group TMPMP (35.28/138) number 3 (TEW: 136-140 g/eq.)Compound T of Thiocure ® 37.59 0.086 thiol eq. functional group ETTMP1300 number 3 (TEW: 435-438 g/eq) Compound E of Kane Ace MX ® 18.670.062 epoxy eq. functional group 154 (EEW: (18.67/301) number 2 301g/eq) Compound T of Epon ®828 7.92 0.042 epoxy eq. functional group(EEW: 185-192 number 2 g/eq.) catalyst DBU 0.54 — Component NameQuantity (in g) Composition of Part B1 PTE1 65.14 Calcium Calofort U17.53 carbonate marketed by Specialty Minerals Silica O Micron NP3-13.93 P0 marketed by Sovitec Organic fillers Expancel 0.25 marketed byNouryon Silica fumes Cabot-Sil TS 3.15 720 marketed by Cabot Compositionof Part A1 modified SR 348 L 92.12 methacrylate marketed by oligomerSartomer ® Pigment Phthalocyanine 0.09 marketed by Heubach Silica fumesCabot-Sil TS 4.07 720 marketed by Cabot Adhesion Dynasilane 3.72promoter 1146 marketed by Evonik

The properties of this sealant are collected in Table 2.

TABLE 2 Property Unit Test method Value Density g/cm3 ISO 2781 1.12Shore A Shore A ISO 868 60 hardness Peel stress N/25 mm AMS 3281 75Shear stress MPa EN 2243-1 1.9

In addition, the application time of the sealant prepared according toExample 1 is 2 hours at room temperature, which corresponds to a classB-2 sealant.

Example 2 Compliant

The polyether prepolymer PTE2 is prepared in the following manner:compounds T are introduced into a container in the quantities mentionedin table 3, then compounds E are added in the quantities mentioned intable 3 as well as the catalyst, and they are stirred. Stirring iscontinued for 40 minutes. The reaction is exothermic, the temperature iscontrolled, which ranges from 20 to 70° C. The polyether PTE2 prepolymerformed is recovered. The ratio number of thiol groups/number of epoxygroups is 4.

Then a mastic composition according to the invention was prepared bymixing 100g of composition Part B2 containing the polyether prepolymerPTE2 according to the invention and 45g of composition Part A2containing a modified methacrylate oligomer. The components of the PartB2 and Part A2 compositions are listed in Table 3.

TABLE 3 Composition of PTE 2 Number of Quantity thiol or epoxy ComponentName (in g) groups Compound T of Thiocure ® 55.35 0.304 thiol eq.functional group TEMPIC number 3 (TEW 180-184 g/eq.) Compound T ofThiocure ® 18.71 0.043 thiol eq. functional group ETTMP 1300 number 3(TEW: 435-438 g/eq) Compound E of Kane Ace 25.48 0.084 epoxy eq.functional group MX ®154 (EEW: number 2 301 g/eq) catalyst DBU 0.46Component Name Quantity (in g) Part B2 Composition PTE2 68.96 CalciumCalofort U 29.54 carbonate Zinc and ZCP marketed 1.17 calcium by Heubachphosphate Adhesion Dynasilane 0.33 promoter MTMO marketed by EvonikComposition of Part A2 modified SR 348 L ® 95.48 methacrylate oligomerPigment Phthalocyanine 0.10 Silica fumes Cabot-Sil TS 3.92 720 AdhesionDynasilane 0.50 promoter MTMO

The properties of this sealant are collected in Table 4.

TABLE 4 Property Unit Test method Value Density g/cm3 ISO 2781 1.35Shore A Shore A ISO 868 40 hardness Peel stress N/25 mm AMS 3281 90Shear stress MPa EN 2243-1 1.2

In addition, the application time of the mastic prepared according toExample 2 is 2 hours at room temperature, which corresponds to a classB-2 mastic.

Comparative Example 3

Then a mastic composition according to the invention was prepared bymixing 100g of composition Part B3 containing the polyether prepolymerPTE2 according to the invention and 13.8 g of composition Part A3containing a diene. The components of the Part B3 and Part A3compositions are listed in Table 5.

TABLE 5 Component Name Quantity (in g) Part B3 Composition PTE2 65.14Calcium Calofort U 17.53 carbonate Silica O Micron NP3-P0 13.93 Organicfillers Expancel 0.25 Silica fumes Cabot-Sil TS 720 3.15 Composition ofPart A3 Diene DEG-DVE 100 marketed by Sartomer ®

The properties of this mastic are collected in Table 8.

TABLE 6 Property Unit Test method Value Density g/cm3 ISO 2781 1.15Shore A Shore A ISO 868 <20 hardness

The hardness of the mastic obtained is very low. In addition, thismastic is only obtained after 3 days of crosslinking at roomtemperature, which is not acceptable.

Furthermore, the polymerization time could not be reduced even byincreasing the level of catalyst.

Example 4 Compliant

The polyether prepolymer PTE4 is prepared in the following manner thecompounds T are introduced into a container in the quantities mentionedin table 7, then compound E is added in the quantities mentioned intable 7 as well as the catalyst, and they are stirred. Stirring iscontinued for 40 minutes. The reaction is exothermic, the temperature iscontrolled, which goes from 20 to 70° C. The polyether PTE4 prepolymerformed is recovered. The ratio number of thiol groups/number of epoxygroups is 3.1.

Then a mastic composition according to the invention was prepared bymixing 100g of composition Part B4 containing the polyether prepolymerPTE4 according to the invention and 138.9 g of composition Part A4containing two modified methacrylate oligomers. The components of thePart B4 and Part A4 compositions are listed in Table 7.

TABLE 7 Composition of PTE 4 Number of Quantity thiol or epoxy ComponentName (in g) groups Compound T of DMDO (TEW: 11.50 0.126 thiol eq.functional 91.15 g/eq.) 11.5/91.15 group number 2 Compound T of Thiocure ® 47.60 0.261 thiol eq. functional TEMPIC (TEW group number 3 180-184g/eq.) Compound E of DER 732 P 40 0.125 epoxy eq. functional (TEW310-330 group number 2 g/eq.) Catalyst DBU 0.90 — Component NameQuantity (in g) Composition of Part B4 PTE4 85.41 Adhesion Hardness 2.56promotor 11078 Catalyst DBU 0.13 Calcium Calofort U 2.91 carbonatemarketed by Specialty Minerals Silica petals Glass flakes 5.23 GF 750 MAdhesion Dynasilane 0.86 promotor MTMO Hollow fillers Expancel 1.27 DE40D30 marketed by Nouryon Pigment Titanium 0.86 dioxide Silica fumesCabot-Sil TS 0.77 720 Composition of Part A4 Modified SR 348 L 53.84methacrylate marketed by oligomer Sartomer ® Modified SR 307 L 8.08methacrylate marketed by oligomer Sartomer ® Silica petals Glass flakes16.00 GF 001 Epoxy Calcium Calofort U 18.72 carbonate PigmentPhthalocyanine 0.02 Silica fumes Cabot-Sil TS 1.72 720 AdhesionDynasilane 1.62 promotor 1146

The properties of this sealant are collected in Table 8.

TABLE 8 Property Unit Test method Value Density g/cm3 ISO 2781 1.35Shore A Shore A ISO 868 55 hardness Peel stress N/25 mm 50 Shear stressMPa EN 2243-1 1.15

Example 5 (Compliant)

The polyether prepolymer PTE5 is prepared in the following manner: thecompounds T are introduced into a container in the quantities mentionedin table 7, then compound E is added in the quantities mentioned intable 9 as well as the catalyst, and they are stirred. Stirring iscontinued for 40 minutes. The reaction is exothermic, the temperature iscontrolled, which goes from 20 to 70° C. The polyether PTE5 prepolymerformed is recovered. The ratio number of thiol groups/number of epoxygroups is 3.0.

Then a mastic composition according to the invention was prepared bymixing 10g of composition Part B5 containing the polyether prepolymerPTE5 according to the invention and 108 g of composition Part A5containing two epoxy prepolymers. The components of the Part B5 and PartA5 compositions are listed in Table 9.

TABLE 9 Composition of PTE 5 Number of Quantity thiol or epoxy ComponentName (in g) groups Compound T of DMDO (TEW: 53.46 0.586 thiol eq.functional group 91.15 g/eq.) number 2 Compound T of Thiocure  ® 1.990.011 thiol eq. functional group TEMPIC (TEW number 3 180-184 g/eq.)Compound E of DER 732 P (TEW 20.94 0.065 epoxy eq. functional group310-330 g/eq.) number 2 Compound E of DER 332 P (TEW 22.94 0.133 epoxyeq. functional group 170-175 g/eq.) number 2 Catalyst DBU 0.67 —Component Name Quantity (in g) Composition of Part B5 PTE5 82.23 SolventEthyl acetate 5.02 Adhesion Hardness 11078 2.47 promotor catalyst DBU0.13 Calcium Calofort U 2.79 carbonate Silica petals Glass flakes GF5.06 750 M Pigment Titanium 0.82 dioxide Adhesion Dynasilane 0.82promotor MTMO Hollow fillers Expancel DE40 0.66 D30 Composition of PartA5 Epoxy DEN 431 26.08 prepolymer Epoxy DEN 332 26.08 prepolymerPlasticizer Benzoflex 9-88 10.95 Silica petals Glass flakes GF 15.28 001Epoxy Calcium Calofort U 18.36 carbonate Pigment Phthalocyanine 0.02Silica fumes Cabot-Sil TS 1.67 720 Adhesion Dynasilane 1146 1.56promotor

The properties of this sealant are collected in Table 10.

TABLE 10 Property Unit Test method Value Density g/cm3 ISO 2781 1.15Shore A Shore A ISO 868 45 hardness Peel stress N/25 mm 120 Shear stressMPa EN 2243-1 1.5

In addition, the application time of the mastic prepared according toExample 5 is 2 hours at room temperature or 30 minutes at 150° C.

1. A polythioether prepolymer comprising thiol functional groups,wherein the polythioether polymer is capable of being obtained by thereaction: of at least one compound T having a number f of thiolfunctional groups selected from 2, 3, 4 and 6, with at least onecompound E having a number g of epoxy functional groups selected from 2and
 3. 2. The polythioether prepolymer according to claim 1, whereinduring the reaction of at least one compound T and at least one compoundE, the compounds T comprising thiol groups and the compounds Ecomprising the epoxy groups react according to a ratio number of thiolgroups:number of epoxy groups from 3:1 to 4:1.
 3. The polythioetherprepolymer according to claim 1 wherein the polythioether polymercomprises pendant hydroxyl functional groups.
 4. The polythioetherprepolymer according to claim 1, wherein the polythioether prepolymer iscapable of being obtained from at least one compound T comprising atleast two groups selected from the group consisting of: b)—(CH₂)_(nb)—SH; c) —(CH₂)_(nc)—O—(CH₂)_(mc)—SH; d)—(CH₂)_(nd)—O—(CO)—(CH₂)_(md)—SH; e) —(CH₂)_(ne)—(CO)—O—(CH₂)_(me)—SH;f) —(CH₂)_(nf)—O—(CH₂CH₂O)_(lf)—(CH₂)_(mf)—SH; g)—(CH₂)_(ng)—(CO)—O—(CH₂CH₂O)_(lg)—(CH₂)_(mg)—SH; h)—(CH₂)_(nh)—O—(CO)—(CH₂CH₂O)_(lh)—(CH₂)_(mh)—SH; i)—(CH₂)_(ni)—O—(CH₂CH₂O)_(lj)—(CO)—(CH₂)_(mi)—SH; j)—(CH₂)_(nj)—O—(CO)—(CH₂CH₂O)_(lj)—(CO)—(CH₂)_(mj)—SH; and k)—(CH₂)_(nk)—(CO)—O—(CH₂CH₂O)_(lk)—(CO)—(CH₂)_(mi)—SH; each of nb, nc,nd, ne, nf, ng, nh, ni, nj, nk being an integer ranging from 0 to 10;each of mc, md, me, mf, mg, mh, mi, mj, mk being an integer ranging from0 to 10; and each of lf, lg, lh, li, lj, lk being an integer rangingfrom 0 to
 6. 5. The polythioether prepolymer according to claim 1,wherein the polythioether prepolymer is capable of being obtained fromat least one compound T of general formula (I):

in which R₁, R₂ and R₃, identical or different, are selected from thegroup consisting of: a) —C₁₋₁₀ alkyl; b) —(CH₂)_(n1b)—SH;C)—(CH₂)_(n1c)—O—(CH₂)_(m1c)—SH; d) —(CH₂)_(n1d)—O—(CO)—(CH₂)_(m1d)—SH;e) —(CH₂)_(n1e)—(CO)—O—(CH₂)_(m1e)—SH; f)—(CH₂)_(n1f)—O—(CH₂CH₂O)_(l1f)—(CH₂)_(m1f)—SH; g)—(CH₂)_(n1g)—(CO)—O—(CH₂CH₂O)_(l1g)—(CH₂)_(m1g)—SH; h)—(CH₂)_(n1h)—O—(CO)—(CH₂CH₂O)_(l1h)—(CH₂)_(m1h)—SH; i)—(CH₂)_(n1i)—O—(CH₂CH₂O)_(l1i)—(CO)—(CH₂)_(m1i)—SH; j)—(CH₂)_(n1j)—O—(CO)—(CH₂CH₂O)_(l1j)—(CO)—(CH₂)_(m1j)—SH; and k)—(CH₂)_(n1k)—(CO)—O—(CH₂CH₂O)_(l1k)—(CO)—(CH₂)_(m1k)—SH; with each ofn1b, n1c, n1d, n1e, n1f, n1g, n1h, n1i, n1j, n1k is an integer rangingfrom 0 to 10; each of m1c, m1d, m1e, m1f, m1g, m1h, m1i, m1j, m1k is aninteger ranging from 0 to 10; and each of l1f, l1g, l1h, l1i, l1j, l1kan integer ranging from 0 to 6; provided that at least two radicals fromthe radicals R₁, R₂ and R₃ are chosen from groups b) to k).
 6. Thepolythioether prepolymer according to claim 1, wherein the polythioetherprepolymer can be obtained from at least one compound T of generalformula (II):

in which R₄, R₅, R₆ and R₇, identical or different, selected from thegroup consisting of: a) —C₁₋₁₀ alkyl; b) —(CH₂)_(n2b)—SH; c)—(CH₂)_(n2c)—O—(CH₂)_(m2c)—SH; d) —(CH₂)_(n2d)—O—(CO)—(CH₂)_(m2d)—SH; e)—(CH₂)_(n2e)—(CO)—O—(CH₂)_(m2e)—SH; f)—(CH₂)_(n2f)O—(CH₂CH₂O)_(l2f)—(CH₂)_(m2f)—SH; g)—(CH₂)_(n2g)—(CO)—O—(CH₂CH₂O)_(l2g)—(CH₂)_(m2g)—SH; h)—(CH₂)_(n2h)—O—(CO)—CH₂CH₂O)_(l2h)—(CH₂)_(m2h)—SH; i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH; j)—(CH₂)_(n2j)—O—(CO)—(CH₂CH₂O)_(l2j)—(CO)—(CH₂)_(m2j)—SH; and k)—(CH₂)_(n2k)—(CO)—O—(CH₂CH₂O)_(l2k)—(CO)—(CH₂)_(m2k)—SH; with each ofn2b, n2c, n2d, n2e, n2f, n2g, n2h, n2i, n2j, n2k being an integerranging from 0 to 10; each of m2c, m2d, m2e, m2f, m2g, m2h, m2i, m2j,m2k being an integer ranging from 0 to 10; each of l2f, l2g, l2h, l2i,l2j, l2k being an integer ranging from 0 to 6; with the proviso that atleast two radicals from the radicals R₄, R₅, R₆ and R₇ are chosen fromgroups b) to k).
 7. The polythioether prepolymer according to claim 6,wherein the polythioether is capable of being obtained from at least onecompound T of general formula (II) in which R₄, R₅ and R₆, which areidentical, are chosen from groups h)—(CH₂)_(n2h)—O—(CO)—(CH₂CH₂O)_(l2h)—(CH₂)_(m2h)—SH or i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH and R₇ is chosen fromthe group a) —C₁₋₁₀ alkyl.
 8. The polythioether prepolymer according toclaim 6, wherein the polythioether prepolymer can be obtained from atleast one compound T with general formula (II) in which R₄, R₅, R₆ andR₇, which are identical, are chosen from the groups h)—(CH₂)_(n2h)—O—(CO)—(CH₂CH₂O)_(l2h)—(CH₂)_(m2h)—SH or i)—(CH₂)_(n2i)—O—(CH₂CH₂O)_(l2i)—(CO)—(CH₂)_(m2i)—SH.
 9. The polythioetherprepolymer according to claim 1, wherein the polythioether prepolymer iscapable of being obtained from at least one compound T of generalformula (III)

in which R₈, R₉, R₁₀, R_(8′), R_(9′) and R_(10′), identical ordifferent, are selected from the group consisting of: a) —C₁₋₁₀ alkyl;b) —(CH₂)_(n3b)—SH; c) —(CH₂)_(n3c)—O—(CH₂)_(m3c)—SH; d)—(CH₂)_(n3d)—O—(CO)—(CH₂)_(m3d)—SH; e)—(CH₂)_(n3e)—(CO)—O—(CH₂)_(m3e)—SH; f)—(CH₂)_(n3f)—O—(CH₂CH₂O)_(l3f)—(CH₂)_(m3f)—SH; g)—(CH₂)_(n3g)—(CO)—O—(CH₂CH₂O)_(l3g)—(CH₂)_(m3g)—SH; h)—(CH₂)_(n3h)—O—(CO)—(CH₂CH₂O)_(l3h)—(CH₂)_(m3h)—SH; i)—(CH₂)_(n3i)—O—(CH₂CH₂O)_(l3i)—(CO)—(CH₂)_(m3i)—SH; j)—(CH₂)_(n3j)—O—(CO)—(CH₂CH₂O)_(l3j)—(CO)—(CH₂)_(m3j)—SH; and k)—(CH₂)_(n3k)—(CO)—O—(CH₂CH₂O)_(l3k)—(CO)—(CH₂)_(m3k)—SH with each ofn3b, n3c, n3d, n3e, n3f, n3g, n3h, n3i, n3j, n3k is an integer rangingfrom 0 to 10; each of m3c, m3d, m3e, m3f, m3g, m3h, m3i, m3j, m3k is aninteger ranging from 0 to 10; and each of l3f, l3g, l3h, l3i, l3j, l3kis an integer ranging from 0 to 6; provided that at least two radicalsfrom the radicals R₈, R₉, R₁₀, R_(8′), R_(9′) and R_(10′), are chosenfrom groups b) to k).
 10. The polythioether prepolymer according toclaim 1, wherein the polythioether prepolymer is capable of beingobtained from at least one compound T of general formula (IV) HS—R₁₁—SHwith R₁₁ chosen from the following groups:—(CH₂)_(q)—(CO)—O—(CH₂CH₂)—O—(CO)—(CH₂)_(s)— or—[(CH₂)_(q)—O]_(r)—(CH₂)_(s)— and —[(CH₂)_(q)—S]_(r)—(CH₂)_(s)—, with qis an integer ranging from 2 to 6, r is an integer ranging from 1 to 5and s is an integer ranging from 2 to
 10. 11. The polythioetherprepolymer according to claim 1, wherein the polythioether prepolymercan be obtained from at least one compound E of formula (V)

with R is a group —C₁₋₆ Alk-O-R′—C₁₋₆ Alk- and R′ is a group comprisingat least one radical chosen from radicals: —C₁₋₆ Alk; —C₁₋₆ Alk-O—;—C₆₋₁₀ Aryl-; and —C₆₋₁₀ Aryl-O—; radicals —C₆₋₁₀ Aryl- and —C₆₋₁₀Aryl-O— being unsubstituted or substituted by at least one group chosenfrom —C₁₋₆ alkyl and epoxide.
 12. The polythioether prepolymer accordingto claim 11, obtainable from a compound E corresponding to formula (VI)

where n ranges from 0 to
 1. 13. The polythioether prepolymer accordingto claim 1, wherein the polythioether prepolymer is capable of beingobtained by the reaction: of at least one compound T selected from thegroup consisting of tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate,triethylolpropane tri(3-mercaptopropionate),ethoxylatedtrimethylolpropanetri(3-mercaptopropionate),dipentaerythritolhexa(3-mercaptopropionate),di(3-mercaptopropionate)glycol, dimercaptodioxaoctane and dimercaptodiethyl sulfur, with at least one compound E selected from bisphenol Adiglycidyl ether and bisphenol F diglycidyl ether.
 14. A method forpreparing the polythioether prepolymer according to claim 1, comprisingat least the following steps: having at least one compound T having anumber f of thiol functional groups selected from 2, 3, 4 and 6; addingto said compound T at least one compound E having a number g of epoxidefunctional groups selected from 2 and 3, adding a catalyst before and/orafter adding said compound E, stirring the reaction mixture comprisingcompound(s) E and compound(s) T and the catalyst, and recovering theobtained polythioether prepolymer.
 15. A composition comprising at leastone polythioether prepolymer according to claim 1 or prepared accordingto a preparation method comprising the following steps: having at leastone compound T having a number f of thiol functional groups selectedfrom 2, 3, 4 and 6; adding to said compound T at least one compound Ehaving a number g of epoxide functional groups selected from 2 and 3,adding a catalyst before and/or after adding said compound E, stirringthe reaction mixture comprising compound(s) E and compound(s) T and thecatalyst, and recovering the obtained polythioether prepolymer, saidpolythioether prepolymer having a thiol functional group number selectedfrom 2, 3, 4, 5 and 6 and an oligomer chosen from modified(meth)acrylate oligomers and oligomers containing epoxy groups, the sumof the functional group numbers of the polythioether prepolymer and ofthe oligomer being greater than
 4. 16. The composition according toclaim 15, further comprising at least one filler chosen from organicfillers and inorganic fillers.
 17. The composition according to claim15, which is a sealant or mastic.